1. Field of the Invention
The present invention relates to a medium access control (MAC) method and a method for transmitting data using the same in a wireless local area network (WLAN); and, more particularly, to a MAC method and a method for transmitting data using the same in WLAN, which perform bandwidth allocation and bandwidth release by a unit of a downlink and an uplink which form a superframe in a WLAN, thereby reducing an amount of information to process for scheduling so as to enable high speed data processing.
This work was supported by the IT R&D program of MIC/IITA [2006-S-002-02, “IMT-Advanced Radio Transmission Technology with Low Mobility”].
2. Description of Related Art
A wireless local area network (WLAN) system adopts a technology for transmitting data using wideband frequency spreading based on narrowband. The WLAN system has been standardized through IEEE 802.11. In the WLAN system, a MAC layer enables a plurality of terminals to access a shared channel. In 802.11 standard, Carrier Sense Multiple Access/Collision Avoidence (CSMA/CA) is generally used as an access method.
FIG. 1 is a diagram illustrating a structure of a MAC protocol.
As shown in FIG. 1, a MAC protocol includes a Frame Control field, a Duration ID (identifier field, four Address fields, a Sequence Control field, a Frame Body field, and a CRC (cyclic redundancy check) field. The Frame Control field includes information on a type of a corresponding frame and fragmentation. The Duration ID field includes information on an association identity (AID) in case of a power save mode or includes a duration value for each frame type for any other cases. The CRC field is for checking error.
A WLAN system supports a bandwidth of about several tens Mbps. In case of 802.11n, the WLAN system supports a bandwidth of about 100 Mpbs. However, newly introduced Ethernet based services request further wider bandwidth. Therefore, it is necessary to develop a WLAN system to provide a wideband of about several Gbps. However, the 802.11 based technology has limitation to support such wideband. In order to overcome the limitation, many studies have been in progress for developing a time division multiple access (TDMA) WLAN system.
A MAC protocol for the TDMA WAN system includes a map field, a downlink field, a poll request field, and an uplink field. The map field includes information on a location and configuration of a subframe. The downlink field stores download data to be transmitted from a wireless base station to a terminal. The poll request field requests a wireless base station and terminals to allocate a bandwidth for subframes. The uplink field stores upload data to be transmitted from a terminal to a wireless base station. Here, the poll request field is included in a bandwidth request transmitted to each of terminals and is also included in a response thereof.
As described above, the MAC protocol requests high speed data processing because the bandwidth allocation request and the response thereof are present in the poll request frame together. If not, the length of the poll request frame must be disadvantageously very long.